This invention relates to the field of high definition television (HDTV) and, more particularly, to an HDTV system which is also compatible with existing television receivers.
In the field of television, whether broadcast, satellite or cable systems, there is much interest in improving picture definition over that provided by the NTSC standards first established in the U.S. in 1953 (NTSC=National Television System Committee). At the present time, over a dozen HDTV systems have been proposed, most of which have not been field-tested. For an overview of many of these systems, see IEEE SPECTRUM, Vol. 25, No. 4, Apr. 1988, pp 56-62.
Some of the proposed systems require only a single channel (6MHz), others one and one-half channels or more. Some of the proposed systems are compatible and use only one channel, others are compatible but use more than one channel, others are incompatible. Many of the systems are designed for the 16:9 aspect ratio often used for motion picture displays, but will not accommodate the full 4:3 frame used in most motion picture production.
An approach which could accommodate the motion picture industry by providing a high quality of reproduction, allowing for various framing options while matching the standard aspect ratio of the present motion picture and television systems, and including compatibility, would be preferable to any of the presently proposed systems.